U.S. patent application number 17/317206 was filed with the patent office on 2021-11-18 for three-state optical article and method for controlling same.
The applicant listed for this patent is Essilor International. Invention is credited to Sylvain CHENE, Bruno FERMIGIER, Samy HAMLAOUI.
Application Number | 20210356768 17/317206 |
Document ID | / |
Family ID | 1000005622565 |
Filed Date | 2021-11-18 |
United States Patent
Application |
20210356768 |
Kind Code |
A1 |
HAMLAOUI; Samy ; et
al. |
November 18, 2021 |
THREE-STATE OPTICAL ARTICLE AND METHOD FOR CONTROLLING SAME
Abstract
The disclosure relates to an optical article which comprises a
hollow chamber and a separator separating the hollow chamber into a
first subspace and a second subspace. The separator comprises an
aperture. The optical article comprises a deformable membrane,
attached, in the second subspace, along a closed line surrounding
the aperture. The optical article is switchable, by deformation of
the membrane, between at least three states (ST1, ST2, ST3). Each
state corresponds to a different optical function. The disclosure
also comprises a corresponding method for switching said optical
article between at least two of the three states.
Inventors: |
HAMLAOUI; Samy;
(Charenton-le-pont, FR) ; CHENE; Sylvain;
(Charenton-le-pont, FR) ; FERMIGIER; Bruno;
(Charenton-le-pont, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Essilor International |
Charenton-le-pont |
|
FR |
|
|
Family ID: |
1000005622565 |
Appl. No.: |
17/317206 |
Filed: |
May 11, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02C 7/085 20130101 |
International
Class: |
G02C 7/08 20060101
G02C007/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 13, 2020 |
EP |
20305494.5 |
Claims
1. Optical article comprising: a hollow chamber delimited by an
outer wall, a separator extending from the outer wall inwards,
comprising a first side facing a first surface of the outer wall
and a second side facing a second surface of the outer wall, the
separator separating the hollow chamber into a first subspace and a
second subspace, wherein the separator comprises an aperture, the
optical article comprises a deformable membrane, attached, in the
second subspace, along a closed line surrounding the aperture, the
deformable membrane separating the hollow chamber into a first
cavity extending towards the first surface of the outer wall and a
second cavity extending towards the second surface of the outer
wall, the optical article is switchable, by deformation of the
membrane, between at least three states, and the first cavity being
filled with a first fluid having a first optical property and the
second cavity being filled with a second fluid having a second
optical property, the optical article has a different optical
function for each of the at least three states.
2. Optical article according to claim 1, wherein the separator and
the outer wall are non-deformable.
3. Optical article according to claim 1, wherein the outer wall
comprises a fluid inlet linked to the first subspace for adjusting
an amount of fluid inside the first cavity to deform the membrane
to switch the active optical function from one state to
another.
4. Optical article according to claim 1, wherein the outer wall
comprises a fluid inlet linked to the second subspace for adjusting
an amount of fluid inside the second cavity to deform the membrane
to switch the active optical function from one state to
another.
5. Optical article according to claim 1, wherein in a first state
the deformable membrane is pressed against the separator such that
the first cavity extends throughout the first subspace while the
second cavity extends throughout the second subspace.
6. Optical article according to claim 1, wherein in a second state
the deformable membrane protrudes through the aperture such that
the second cavity extends to part of the first subspace.
7. Optical article according to claim 6, wherein in a third state
at least part of the deformable membrane is lifted off the
separator such that the first cavity extends to at least part of
the second subspace.
8. Optical article according to claim 1, wherein the at least part
of the deformable membrane has an area larger than the
aperture.
9. Optical article according to claim 8, wherein in the third state
at least part of the deformable membrane is pressed against the
second surface of the outer wall.
10. Optical article according to claim 1, wherein the aperture has
a circular section.
11. Optical article according to claim 1, wherein the optical
article is an optical lens comprising a front shell and a back
shell and wherein the hollow chamber is formed between the front
shell and the back shell.
12. Optical article according to claim 1, wherein, the first cavity
being filled with a first fluid and the second cavity being filled
with a second fluid, the optical article has a first optical power
P1 in the first state and a second optical power P2 in the second
state with P2-P1 having an absolute value greater than 0.25
diopters.
13. Optical article according to claim 1, wherein, the first cavity
being filled with a first fluid and the second cavity being filled
with a second fluid, the optical article has a first optical power
P1 in the first state and a third optical power P3 in the third
state with P3-P1 having an absolute value greater than 0.25
diopters.
14. Optical article according to claim 1, wherein the separator
comprises a plurality of apertures and the membrane is attached, in
the second subspace, across a closed shape surrounding the
plurality of apertures.
15. Method for switching an optical function of an optical article
comprising: a hollow chamber delimited by an outer wall, a
separator extending from the outer wall inwards, comprising a first
side facing a first surface of the outer wall and a second side
facing a second surface of the outer wall, the separator separating
the hollow chamber into a first subspace and a second subspace, the
separator comprising a central aperture, a deformable membrane,
attached to a peripheral area in the second subspace, the
deformable membrane separating the hollow chamber into a first
cavity extending towards the first surface of the outer wall and a
second cavity extending towards the second surface of the outer
wall, the optical article having an active optical function which
is switchable, by deformation of the membrane, between at least
three states, the method comprising switching the optical function
of the optical article between two of the at least three states by
deforming the membrane.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to EP 20305494.5 filed May
13, 2020, the entire contents of which is hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates in general to optical articles
such as eyewear or eyewear components and to methods for switching
such optical articles.
BACKGROUND OF THE INVENTION
[0003] Some known optical lenses may provide a variable lens power
using a deformable membrane that separates two liquids having
different refractive indices.
[0004] One difficulty with these known optical lenses is that a
compromise is required between providing a large field of view and
providing a large power modification range.
[0005] Document WO2006011937 describes an example of an optical
lens.
[0006] The amplitude of the allowable power variation over a large
field is limited by the amplitude of the allowable deformation of
the membrane, thus to the thickness of the optical lens. In this
example, the difference of refractive index between the 2 liquids
is limited to about 0.1 or 0.2. For this reason, an optical power
variation such as over a range of 3 diopters over a full lens field
is unattainable in practice.
[0007] Such an optical lens may only be applicable to provide small
power changes over a full lens field.
[0008] The potential use of such an optical lens is to provide, to
a limited extent, an adapted optical power in a far vision
situation to provide a correction adapted to an evolutive myopia.
However, such an optical lens cannot provide a variable optical
power in a near vision situation to correct an evolutive hyperopia
or presbyopia.
[0009] Document US 2019227346 describes another example of optical
lens.
[0010] A larger optical power variation, such as over a range of 3
diopters, may be achievable, but since the allowable width of the
deformation of the membrane is limited by the thickness of the
optical lens, such an optical power variation may only be provided
over a part of the lens field. The potential use of such an optical
lens is to provide a variable optical power over a limited field of
view in a near vision situation to correct an evolutive hyperopia
or presbyopia. However, such an optical lens cannot provide an
adapted optical power over a large field of view, thus cannot
provide a correction adapted to an evolutive myopia.
[0011] In this context, there is a need for an improved optical
lens that may not only provide a power variation across a large
field of view but also provide a large range of power
variation.
[0012] Such an optical lens shall also remain structurally
simple.
SUMMARY OF THE INVENTION
[0013] Embodiments of the invention provide an optical article
comprising:
[0014] a hollow chamber delimited by an outer wall,
[0015] a separator extending from the outer wall inwards,
comprising a first side facing a first surface of the outer wall
and a second side facing a second surface of the outer wall, the
separator separating the hollow chamber into a first subspace and a
second subspace,
[0016] wherein the separator comprises an aperture,
[0017] the optical article comprises a deformable membrane,
attached, in the second subspace, along a closed line surrounding
the aperture, the deformable membrane separating the hollow chamber
into a first cavity extending towards the first surface of the
outer wall and a second cavity extending towards the second surface
of the outer wall,
[0018] the optical article is switchable, by deformation of the
membrane, between at least three states, and
[0019] the first cavity being filled with a first fluid having a
first optical property and the second cavity being filled with a
second fluid having a second optical property, the optical article
has a different optical function for each of the at least three
states.
[0020] Embodiments of the invention further provide a method for
switching an optical function of an optical article comprising:
[0021] a hollow chamber delimited by an outer wall,
[0022] a separator extending from the outer wall inwards,
comprising a first side facing a first surface of the outer wall
and a second side facing a second surface of the outer wall, the
separator separating the hollow chamber into a first subspace and a
second subspace, the separator comprising a central aperture,
[0023] a deformable membrane, attached to a peripheral area in the
second subspace, the deformable membrane separating the hollow
chamber into a first cavity extending towards the first surface of
the outer wall and a second cavity extending towards the second
surface of the outer wall,
[0024] the optical article having an active optical function which
is switchable, by deformation of the membrane, between at least
three states,
[0025] the method comprising switching the optical function of the
optical article between two of the at least three states by
deforming the membrane.
[0026] By "a closed line surrounding the aperture" is understood a
closed line delimiting a closed surface of the outer wall and/or of
the separator, the closed surface forming an area greater than the
aperture and fully covering the aperture.
[0027] By "fluid" is understood any liquid or gas. By selecting
fluids having refractive indices close to the refractive indices of
the materials forming the separator, the membrane and the hollow
chamber, light reflections may be minimized
[0028] The expressions "optical function" and "optical property"
may respectively include in particular a dioptric function and a
refraction index.
[0029] For example, the first fluid and the second fluid may have
different refraction indices, then the optical article has a
different dioptric function for each of the at least three
states.
[0030] It is thus possible, using such an optical article or
performing such a method, to provide an optical function which is
variable between at least three states in a simple and efficient
way. Indeed, it is possible, by deforming the membrane, to switch
from a first state to a second state so as to provide for example a
variation of optical power across a large field of view, and to
switch from the first state to the third state so as to provide for
example a larger variation of optical power across a narrower field
of view.
[0031] This is achieved by the specific configuration of the
optical article, in particular of the separator and of the
membrane, to permit a different membrane deformation in both
directions. In a first direction, the membrane only may be deformed
in a limited area delimited by the aperture while in the second
direction the membrane may be deformed over a larger area
encompassing the aperture.
[0032] The expressions "optical function" and "optical property"
may respectively include in particular a transmission function and
a visible light absorption spectrum.
[0033] For example, the first fluid and the second fluid may have
different visible light absorption spectra, then the optical
article has a different transmission function and a different tint
for each of the at least three states.
[0034] Of course, the first fluid and the second fluid may also
have both different refraction indices and different visible light
absorption spectra.
[0035] In an example, the separator is non-deformable.
[0036] In this example, the deformation of the membrane is limited
by the shape of the separator. The shape of the separator may be
selected for example such that if the membrane is held against the
separator and both cavities are filled with a different fluid the
resulting optical function of the optical article is predefined.
For example, the resulting optical power may then be equal to a
predetermined prescription value.
[0037] In an example, the outer wall is non-deformable.
[0038] In this example, the deformation of the membrane is limited
by the shape of the hollow chamber. The shape of the hollow chamber
may be selected for example such that if the membrane is held
against the outer wall of the hollow chamber and both cavities are
filled with a different fluid, the resulting optical function of
the optical article is predefined. For example, the resulting
optical power may then be equal to a predetermined value suitable
for correcting a defect of an eye of a user during, for example, a
far distance activity.
[0039] When both the outer wall and the separator are
non-deformable, the deformation of the membrane is the single
controllable parameter for switching the optical article between
different states.
[0040] In an example, the outer wall comprises a fluid inlet linked
to the first subspace for adjusting an amount of fluid inside the
first cavity to deform the membrane to switch the active optical
function from one state to another.
[0041] In an example, the outer wall comprises a fluid inlet linked
to the second subspace for adjusting an amount of fluid inside the
second cavity to deform the membrane to switch the active optical
function from one state to another.
[0042] In general, the deformation of the membrane may be
controllable by adjusting:
[0043] an amount of fluid in either cavity, or
[0044] amounts of fluids in both cavities, or
[0045] a difference of pressure in both cavities.
[0046] The following examples illustrate different possible states
of the optical article.
[0047] Each of these exemplary states corresponds to a specific
position of the deformable membrane, resulting in specific shapes
of the first cavity and of the second cavity.
[0048] In an example, in a first state the deformable membrane is
pressed against the separator such that the first cavity extends
throughout the first subspace while the second cavity extends
throughout the second subspace.
[0049] In this example, the first state may be considered as a
default, or reference, state.
[0050] When both cavities are filled with a fluid having a
different optical property, the optical article provides a
reference optical function. The reference optical function is
related to the shape of the separator, which may be planar,
spherical, toroidal, freeform, etc.
[0051] depending on the particular needs of a user. For example,
the reference optical function may be based on a prescription value
of the user. For example, the reference optical function may be
adapted to the user for an intermediate distance vision
activity.
[0052] In an example, in a second state the deformable membrane
protrudes through the aperture such that the second cavity extends
to part of the first subspace.
[0053] In this example, the second state may be considered as a
state for a specific use, such as for near vision activities.
[0054] For example, the deformable membrane may be pressed against
the separator, as in the first state, with the exception that the
membrane protrudes through the aperture.
[0055] In this example, when both cavities are filled with a fluid
having a different optical property, the optical article provides
the reference optical function over most of the full field, that
is, over the separator excluding over the aperture. In addition,
the optical article provides a specific optical function over a
narrow part of the full field, that is, over the aperture.
[0056] For example, the shape and section of the aperture, along
with the width of the protrusion over the aperture may be chosen to
provide, over the aperture, a specific optical function adapted to
a near vision activity.
[0057] For example, the position of the aperture in the separator
may be chosen to correspond to an area of the optical article
corresponding to a range of lowering gaze angles which is best
adapted for correcting an ametropia during a near vision
activity.
[0058] In an example, in a third state at least part of the
deformable membrane is lifted off the separator such that the first
cavity extends to at least part of the second subspace.
[0059] In this example, when both cavities are filled with a fluid
having a different optical property, the optical article provides a
specific optical function, which is different from the reference
optical function, over an area delimited by the closed line the
membrane is attached to.
[0060] The combination of the first, second and third exemplary
states above allows the optical article to provide an optical power
variation throughout a first range over a full field, and also to
provide an optical power variation throughout a second range
greater than the first range, over a narrower field.
[0061] In an example, the at least part of the deformable membrane
has an area larger than the aperture.
[0062] Since the section of the aperture is narrower than the
surface delimited by the closed line the deformable membrane is
attached to, the deformable membrane may be deformed across the
narrow section of the aperture, and may also be deformed across the
greater surface of the area delimited by said closed line.
[0063] In an example, in the third state at least part of the
deformable membrane is pressed against the second surface of the
outer wall.
[0064] The first surface of the outer wall is a depth stop to the
allowable extent of the deformation of the membrane. The shape of
the first surface of the outer wall may be chosen so that the
optical article provides a specific optical function in the third
state. For example, said specific optical function may be adapted
for correcting an ametropia during a far vision activity.
[0065] In an example, the aperture has a circular section.
[0066] Therefore, in the second state, the protrusion of the
membrane through the aperture is spherical and does not induce any
optical aberrations.
[0067] Of course, the section of the aperture may alternatively be
chosen to be non-circular, in order to induce an optical aberration
to specifically correct a specific type of ametropia.
[0068] In an example, the optical article is an optical lens
comprising a front shell and a back shell and the hollow chamber is
formed between the front shell and the back shell.
[0069] For example, the front shell and the back shell each
comprise an external surface on the outside of the optical lens and
an internal surface on the inside of the optical lens. The internal
surfaces form part of the outer wall of the hollow chamber.
[0070] For example, in the third state at least part of the
deformable membrane may be pressed against the internal surface of
the front shell and in the second state the deformable membrane may
protrude through the aperture, facing towards the internal surface
of the back shell.
[0071] For example, in the third state at least part of the
deformable membrane may be pressed against the internal surface of
the back shell and in the second state the deformable membrane may
protrude through the aperture, facing towards the internal surface
of the front shell.
[0072] In an example, the first cavity being filled with a first
fluid and the second cavity being filled with a second fluid, the
optical article has a first optical power P1 in the first state and
a second optical power P2 in the second state with P2-P1 having an
absolute value greater than 0.25 diopters.
[0073] In an example, the first cavity being filled with a first
fluid and the second cavity being filled with a second fluid, the
optical article has a first optical power P1 in the first state and
a third optical power P3 in the third state with P3-P1 having an
absolute value greater than 0.25 diopters.
[0074] 0.25 diopters is the usual measurement step used by
optometrists to determine a refractive error of the eye and is
accordingly also the usual increment of optical power correction
that may be provided to a user.
[0075] In an embodiment, the separator comprises a plurality of
apertures and the membrane is attached, in the second subspace,
across a closed shape surrounding the plurality of apertures.
[0076] The plurality of apertures may be designed, in terms of
respective shapes, sections and/or positions so as to form a
plurality of microlenses when the membrane is deformed to protrude
through the plurality of apertures.
[0077] Microlenses are known to be beneficial in particular for
children having an evolutive myopia.
[0078] For example, the optical article may be configured so
that:
[0079] by switching the optical article between a first and a
second state, an evolutive ametropia in far vision may be corrected
in full field, and
[0080] by switching the optical article between the first state and
a third state in which microlenses are activated by deformation of
the membrane, an evolutive ametropia in near vision may be
corrected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0081] For a more complete understanding of the description
provided herein and the advantages thereof, reference is now made
to the brief descriptions below, taken in connection with the
accompanying drawings and detailed description, wherein like
reference numerals represent like parts.
[0082] FIGS. 1, 2 and 3 depict three example states of a first
example of optical equipment.
[0083] FIG. 4 depicts an example of a general flowchart of a method
according to an embodiment, for controlling the optical equipment
of FIGS. 1, 2 and 3.
[0084] FIGS. 5, 6 and 7 depict three example states of a second
example of optical equipment.
[0085] FIGS. 8 and 9 are maps of wearer power error over a cone of
gaze directions for, respectively, an example of optical equipment
having a toroidal back shell, and an example of optical equipment
having a freeform back shell, both in a first state.
[0086] FIGS. 10 and 11 are maps of resulting astigmatism over a
cone of gaze directions for said examples of optical equipments,
both in said first state.
DETAILED DESCRIPTION OF THE INVENTION
[0087] In the description which follows the drawing figures are not
necessarily to scale and certain features may be shown in
generalized or schematic form in the interest of clarity and
conciseness or for informational purposes. In addition, although
making and using various embodiments are discussed in detail below,
it should be appreciated that as described herein are provided many
inventive concepts that may be embodied in a wide variety of
contexts. Embodiments discussed herein are merely representative
and do not limit the scope of the invention. It will also be
obvious to one skilled in the art that all the technical features
that are defined relative to a process can be transposed,
individually or in combination, to a system and conversely, all the
technical features relative to a system can be transposed,
individually or in combination, to a process.
[0088] It is now referred to FIG. 1, which depicts an example of an
optical lens, such as a spectacle optical lens that may be mounted
on a spectacle frame.
[0089] The optical lens comprises a front lens shell and a back
lens shell.
[0090] The front lens shell and the back lens shell each comprise a
front surface intended to face a visual scene and a back surface
intended to face an eye of a wearer.
[0091] The front shell and the back shell may be both mounted on a
supporting element on the side of the optical lens. Alternately,
the front shell and the back shell may each extend to the side of
the lens and comprise side elements configured to cooperate with
each other.
[0092] The optical lens comprises a hollow chamber (100) delimited
by an outer wall (101) formed in particular by the front surface of
the back shell and the back surface of the front shell.
[0093] In the example illustrated in FIG.1, the back surface of the
front shell may be viewed as a first surface (101a) of the outer
wall (101) and the front surface of the back shell as a second
surface (101b) of the outer wall (101).
[0094] The optical lens further comprises a separator (102). The
separator (102) extends from a side of the outer wall (101)
inwards.
[0095] The separator (102) separates the hollow chamber (100) into
a first subspace (100a) and a second subspace (100b). The separator
comprises a first side (102a) and a second side (102b). The first
subspace (100a) is delimited by the first side (102a) of the
separator (102) and by the first surface (101a) of the outer wall
(101). The second subspace (100b) is delimited by the second side
(102b) of the separator (102) and by the second surface (101b) of
the outer wall (101).
[0096] The separator (102) comprises at least one aperture (103),
possibly a plurality of apertures (103), each aperture being a
channel between the first subspace (100a) and the second subspace
(100b).
[0097] The optical lens further comprises a deformable membrane
(200), in other words a thin piece of material which may be
controllably deformed.
[0098] The membrane (200) is attached, in the second subspace
(100b) along a closed line surrounding the aperture (103). For
example, the closed line may be formed on the second side (102b) of
the separator (102) and delimit an area greater than the aperture
(103) and fully covering the aperture (103). For example, the
closed line may extend along the side of the optical lens, over the
full circumference of the optical lens, and delimit an area
corresponding to the full lens field.
[0099] On the exemplary optical lens depicted in FIG. 1, the
membrane (200) is attached in the second subspace (100b) which
extends from the separator (102) to the back lens shell.
[0100] Of course, on another exemplary optical lens (not
represented), this configuration may be reversed and the membrane
(200) be attached in a first subspace (100a) which extends from the
separator (102) to the front lens shell, while a second subspace
(100b) extends from the separator (102) to the back lens shell.
[0101] The membrane (200) separates the hollow chamber (100) into a
first cavity (201) and a second cavity (202).
[0102] The optical article may be configured so that a given fluid
initially located in the first cavity (201) cannot be displaced
towards the second cavity (202) and vice versa. In particular, the
deformable membrane, the separator, the front shell and the back
shell are all impermeable at least to liquids, and possibly
impermeable to fluids.
[0103] The outer wall (101) may comprise a fluid inlet as a channel
between one of the first cavity and the second cavity, on the one
hand, and the outside of the hollow chamber, on the other hand The
fluid inlet may be coupled to a fluid tank, such that a fluid can
be controllably displaced between the fluid tank to said cavity and
vice versa.
[0104] The outer wall (101) may comprise:
[0105] a first fluid inlet as a first channel between the first
cavity and the outside of the hollow chamber, and
[0106] a second fluid inlet as a second channel between the second
cavity and the outside of the hollow chamber.
[0107] Each fluid inlet may be coupled to a corresponding fluid
tank, such that a fluid (which may be a liquid or a gas) can be
controllably displaced between a fluid tank to the corresponding
cavity and vice versa.
[0108] For example, the optical lens may be a spectacle lens
mounted on a spectacle frame, the fluid inlet may be located on the
side of the spectacle lens, may cooperate with a corresponding hole
in a peripheral holder, towards an arm of the spectacle frame, and
the fluid tank may be coupled with said corresponding hole and be
for example located on, or enclosed in, said arm of the spectacle
frame.
[0109] The optical article is switchable, by deformation of the
membrane (200) between at least three configurations or states
(ST1, ST2, ST3).
[0110] The different configurations or states differ from each
other in the position and shape of the membrane (200) with respect
to the separator (102) and to the outer wall (101). Each of these
different positions and shapes results in a specific partition of
the hollow chamber (100) into the first cavity (201) and the second
cavity (202). In other words, for each state or configuration of
the optical lens, the first cavity (201) has a corresponding first
shape and a corresponding first volume, and the second cavity (202)
has a corresponding second shape and a corresponding second
volume.
[0111] As illustrated in FIG. 1, the optical article may be set in
a first state (ST1) in which the membrane (200) is maintained
against the separator (102) on its whole surface. In other words,
in the first state (ST1), the first subspace (100a) coincides with
the first cavity (201) and the second subspace (100b) coincides
with the second cavity (202).
[0112] In an example, the front lens shell, the back lens shell and
the separator (102) may each be made of a material that is mostly
transparent to visible light. Moreover, the materials forming the
front lens shell, the back lens shell and the separator may have
refractive indices that are close to each other in order to avoid
parasite light reflections.
[0113] In an example, the first cavity (201) may be filled with a
first fluid and the second cavity may be filled with a second
fluid.
[0114] The first fluid and the second fluid are different fluids,
which have different optical properties. In particular, the first
fluid and the second fluid may have different refractive indices,
for example at least a 0.01 difference, possibly 0.05 or more,
possibly 0.1 or more. In particular the first fluid and the second
fluid may have different light absorption spectra, different
tints.
[0115] The first fluid and the second fluid may be appropriately
selected to each have refractive indices close to each other, as
well as close to the refractive indices of the materials forming
the separator (102), membrane, front shell and back shell.
[0116] In the first state, the first cavity (201) being filled with
the first fluid and the second cavity (202) being filled with the
second fluid, the optical article has a first optical function. The
optical function comprises in particular a transmission function
which is related to the absorption spectra of both fluids, to the
absorption spectrum of the different components of the optical
article, such as the membrane (200) and to the respective widths of
both cavities (201, 202).
[0117] The optical function further comprises a dioptric function
which is related to the refractive indices of both fluids, to the
refractive indices of the different components of the optical
article, such as the membrane (200), and to the shapes of the front
and back surfaces of the front shell, of both sides (102a, 102b) of
the separator (102), and of the front and back surfaces of the back
shell.
[0118] It is now referred to FIG. 2, which illustrates a second
exemplary state of the optical article.
[0119] As illustrated in FIG. 2, the optical article may be set in
a second state (ST2) in which the membrane (200) is maintained
against the separator (102) on its whole surface except over the
aperture (103), and in which the membrane (200) protrudes through
the aperture (103).
[0120] The second state may correspond for example to a specific
correction when reading for aging users with presbyopia, or to
provide an additional optical power to help reducing myopia
progression for children users.
[0121] Possibly, the optical article may allow additional near
vision states that are intermediate, in terms of deformation of the
membrane and of resulting optical function, between the first state
as a default optical function and the second state corresponding to
a near vision adjustment extremum. Such additional states may each
correspond to adjustment increments of the optical function in near
vision. The optical article may thus allow correcting,
incrementally, an evolution of an ametropia in near vision, up to
the near vision adjustment extremum.
[0122] It is now referred to FIG. 4 which illustrates different
states of the optical article, in relation with an exemplary method
for switching the optical article.
[0123] The method may comprise switching from one state to another.
Switching SW ST1/ST2 the optical article from the first state (ST1)
to the second state (ST2), or from the first state (ST1) to an
additional near vision state (ST121, ST122), or from a first
additional near vision state (ST121) to a second additional near
vision state (ST122), or from an additional near vision state
(ST121, ST122) to the second state (ST2), may be performed for
example by controllably decreasing an amount of the first fluid
filling the first cavity (201) and/or by controllably increasing an
amount of the second fluid filling the second cavity (202). In
order to passively maintain the same pressure in both cavities
(201, 202), the deformable membrane (200) is thus deformed towards
the first surface (101a) of the outer wall (101) of the hollow
chamber (100). Since the membrane abuts against the separator (102)
except over the aperture (103), a protrusion is necessarily formed
through the aperture (103), the size of the protrusion being
related to the respective amounts of fluid in the first cavity
(201) and in the second cavity (202).
[0124] Of course, such switching is reversible by controllably
increasing an amount of the first fluid filling the first cavity
(201) and/or by controllably decreasing an amount of the second
fluid filling the second cavity (202).
[0125] It is now referred to FIG. 3, which illustrates a third
exemplary state of the optical article.
[0126] As illustrated in FIG. 3, the optical article may be set in
a third state (ST3) in which the membrane (200) is lifted off the
separator (102) and at least part of the membrane (200) is pressed
against the second surface (101b) of the outer wall (101).
[0127] Possibly, the optical article may allow additional far
vision states that are intermediate, in terms of deformation of the
membrane and of resulting optical function, between the first state
as a default optical function and the third state corresponding to
a far vision adjustment extremum. Such additional states may each
correspond to adjustment increments of the optical function in far
vision. The optical article may thus allow correcting,
incrementally, an evolution of an ametropia in far vision, up to
the far vision adjustment extremum.
[0128] It shall be noted that in the additional far vision states,
the deformation of the membrane is such that the membrane is
neither pressed against the separator nor against the back lens
shell. Rather, the deformation of the membrane, induced by the
respective pressures of the fluids in both cavities is essentially
spherical.
[0129] In the additional far vision states, the membrane (200) is
lifted off the separator (102), though without being pressed
against the second surface (101b) of the outer wall (101).
[0130] Switching SW ST1/ST3 the optical article from the first
state (ST1) to the third state (ST3), or from the first state (ST1)
to an additional far vision state (ST131, ST132), or from a first
additional far vision state (ST131) to a second additional far
vision state (ST132), or from an additional far vision state
(ST131, ST132) to the second state (ST3), may be performed for
example by controllably increasing an amount of the first fluid
filling the first cavity (201) and/or by controllably decreasing an
amount of the second fluid filling the second cavity (202). In
order to passively maintain the same pressure in both cavities
(201, 202), the deformable membrane (200) is thus deformed towards
the second surface (101b) of the outer wall (101) of the hollow
chamber (100), thus the surface of the membrane (200) delimited by
the closed line is necessarily lifted off the separator (102). In
the third state (ST3) which is extremal, the respective amounts of
fluid in the first cavity (201) and in the second cavity (202) are
such that the membrane (200) abuts against the second surface
(101b) of the outer wall (101) and can't be further deformed.
[0131] Of course, such switching is reversible by controllably
decreasing an amount of the first fluid filling the first cavity
(201) and/or by controllably increasing an amount of the second
fluid filling the second cavity (202).
[0132] The optical lens herein described allows switching between
three different optical functions when the first cavity and the
second cavity are each filled with a different fluid:
[0133] in the first state (ST1), the optical lens may provide for
example an optical function adapted for far vision over a wide
angle,
[0134] in the second state (ST2), the optical lens may provide for
example an optical function adapted for near vision over a narrower
angle, and
[0135] in the third state (ST3), the optical lens may provide for
example an optical function for far vision over a wide angle that
differs from that provided in the first state.
[0136] For a hyperopic wearer, the optical function provided in the
third state (ST3) corresponds to a more positive optical power than
the optical function provided in the first state (ST1).
[0137] For a myopic wearer, the optical function provided in the
third state (ST3) corresponds to a more negative optical power than
the optical function provided in the first state (ST1).
[0138] The optical power difference between the first state (ST1)
and the third state
[0139] (ST3) far vision state are limited, but may apply up to a
full field.
[0140] Indeed, as mentioned above, the membrane (200) is deformed
in the third state across an area delimited by a closed line, and
said closed line may extend to an area comprising a large surface
of the second side (102b) of the separator (102), for example more
than 50%, more than 75% or more than 90% and up to 100%.
[0141] The optical power difference between the first state (ST1)
and the second state (ST2) may reach up to 3 diopters, thanks to
the same membrane that is deformed in the opposite direction over a
limited area. Indeed, as mentioned above, the membrane (200) is
deformed in the second state across an area delimited by the
aperture (103), and said aperture may represent a limited surface
of the second side (102b) of the separator (102), for example less
than 50%, less than 30%, or less than 10%.
[0142] It is now referred to another example of an optical lens,
such as a spectacle optical lens that may be mounted on a spectacle
frame. This other example of optical lens only differs from that
depicted on FIG. 1 in that the separator (102) comprises a
plurality of apertures (103) and in that the membrane (200) is
attached, in the second subspace (100a), across a closed shape
surrounding the plurality of apertures (103).
[0143] This other example of optical lens is also switchable
between at least three different states or configurations. A first
state (ST1) is depicted on FIG. 5, a second state (ST2) is depicted
on FIG. 6 and a third state (ST3) is depicted on FIG. 7.
[0144] In the first state (ST1), the membrane (200) is maintained
against the separator (102) and over the apertures (103), thus the
first subspace (100a) coincides with the first cavity (201) and the
second subspace (100b) coincides with the second cavity (202).
[0145] In the second state (ST2), the membrane (200) is maintained
against the separator (102) and protrudes through each of the
apertures (103), thus the second cavity (202) extends throughout
the second subspace (100b) and part of the first subspace
(100a).
[0146] The apertures (103) may be configured, in their sizes and
shapes, so that when the first cavity (201) and the second cavity
(202) are each filled with a different fluid, each protrusion
behaves optically as a microlens.
[0147] Of course, to obtain such protrusions, it is required that
the material forming the membrane (200) has, at least locally over
the apertures (103), mechanical properties that allow protruding
through said apertures (103).
[0148] From what precedes, the optical lens functionally comprises
microlenses that are inactive in the first state (ST1) and
activated in the second state (ST2).
[0149] Some types of repartition of microlenses over an optical
lens field are known to allow providing an active function in order
to prevent or reduce myopia progression. An appropriate correction
is provided for near vision while also requiring accommodation from
the user, which prevents an evolution of a myopia over time. This
example is typically interesting for child users.
[0150] The repartition of the apertures (103) over the separator
(102) may be chosen so that in the second state (ST2), the optical
lens is adapted to prevent said evolution of myopia over time.
[0151] In the third state, the membrane (200) is released from the
separator (102), thus the microlenses are also inactive and the
optical function provided by the optical lens is different from the
first state. Switching the optical lens between the first state,
the third state, and possible intermediate states between the first
and third states, may allow providing an appropriate correction for
far vision.
EXAMPLES
[0152] A first optical lens configuration for a hyperopic wearer is
described thereafter.
[0153] The lens is composed of a front shell and a back shell
disposed so as to form a hollow chamber. The lens further comprises
a separator separating the hollow chamber into a front subspace
(towards the front shell) and a back subspace (towards the back
shell). The lens further comprises a membrane attached to the side
of the separator facing the back shell. The separator comprises an
aperture as a channel between the front subspace and the back
subspace. The membrane separates the hollow chamber into a first
cavity filled with a first liquid and a second cavity filled with a
second liquid.
[0154] Incoming light generally goes through the lens through the
front shell, the first cavity, the separator, the membrane, the
second cavity and the back lens shell in this order.
[0155] The front shell material, the first liquid, the separator
and the membrane all have the same refractive index, which is equal
to a first value n.sub.1.
[0156] The back shell material and the second liquid have the same
refractive index which is equal to a second value n.sub.2 which is
greater than n.sub.1.
[0157] In practice, it is not possible to have exactly the same
indices between materials and liquids, but it is important that
they are chosen as close as possible to avoid undesired
reflections, which would lower the image quality. For simplicity
purposes, we will assume however, in this example, that these
indices are exactly the same.
[0158] For clarity purposes, the surfaces of the front shell and of
the rear shell will further be assumed to all be spherical, and the
separator will be assumed to be planar. This configuration only
allows providing purely spherical optical powers, such as
corresponding to a spherical prescription value. An extension to
cylindrical optical powers will be presented afterwards.
[0159] In the first state, the membrane rests on the separator and
has a plane shape.
[0160] Using a thin lens approximation, the optical power Pi
provided by the optical lens in the first state is a function of
the curvature ci of the front shell, of the curvature c.sub.3 of
the rear shell, and of the first and second values of refractive
indices ni and n.sub.2, according to the equation
P.sub.1=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3.
[0161] In the second state, the fluid pressure in the second cavity
is increased with respect to the fluid pressure in the first
cavity, which in turn induces a deformation of the membrane which
thus protrudes through the aperture, the protrusion having a
curvature c.sub.22 which has a strictly positive value. Also using
a thin lens approximation, the optical power P.sub.2 provided by
the optical lens over the aperture in the second state is a
function of the curvature c.sub.1 of the front shell, the curvature
c.sub.22 of the protrusion of the membrane through the aperture, of
the curvature c.sub.3 of the rear shell, and of the first and
second values of refractive indices n.sub.1 and n.sub.2, according
to the equation
P.sub.2=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.2)c.sub.3.
Since in the second state the optical lens is intended to correct
for near vision, P.sub.2 is greater than P.sub.1.
[0162] In the third state, the fluid pressure in the first cavity
is increased with respect to the fluid pressure in the second
cavity so as to remove most, or all, of the fluid contained in the
second cavity. The membrane then rests on the back shell and has
the same curvature c.sub.3. Also using a thin lens approximation,
the optical power P.sub.3 provided by the optical lens in the first
state is a function of the curvature ci of the front shell, of the
curvature c.sub.3 of the rear shell and of the membrane, and of the
first and second values of refractive indices n.sub.1 and n.sub.2,
according to the equation
P.sub.3=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.3+(1-n.sub.2)c.sub.3.
[0163] Based on the equations above, the optical lens, in
particular the separator, the front lens shell and the rear lens
shell, may be designed so that the curvatures c.sub.1, c.sub.22 and
c.sub.3 have specific values, based on predetermined values of
P.sub.1, P.sub.2 and P.sub.3 for a particular hyperopic wearer,
such as:
c 1 = P 1 .function. ( n 1 - n 2 ) + ( P 1 - P 3 ) .times. ( n 2 -
1 ) ( n 1 - 1 ) .times. ( n 1 - n 2 ) .times. .times. c 2 .times. 2
= P 1 - P 2 n 1 - n 2 .times. .times. c 3 = P 1 - P 3 n 1 - n 2
##EQU00001##
[0164] Therefore, the exemplary lens described above may
provide:
[0165] in the first state, a first optical power P.sub.1, having a
positive value, over a full field,
[0166] in the second state, a second optical power
P.sub.2>P.sub.1 over a narrow field, the first optical power
P.sub.1 elsewhere, and
[0167] in the third state, a third optical power P.sub.3>P.sub.1
over the full field.
[0168] The first state may be used for example as a standard state
for everyday use, the second state for near vision and the third
state for a specific type of activity in far vision requiring an
improved correction.
[0169] The same optical lens configuration may also be applied for
an exemplary lens for a myopic wearer.
[0170] Alternatively, a second optical lens configuration may be
adapted for an exemplary lens for a myopic wearer.
[0171] In particular, the membrane may be attached to the side of
the separator facing the front shell rather than the back shell,
and the separator may have the same refractive index n.sub.2 as the
second fluid rather than the first fluid. In this configuration,
the curvature value c.sub.22 of the membrane holds a negative value
in the second state.
[0172] The formulas to calculate P.sub.1 and P.sub.2 are unchanged
compared to the previously described configuration, thus
P.sub.1=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3 and
P.sub.2=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.2)c.sub.3.
[0173] Only the formula to calculate P.sub.3 is modified to
P.sub.3=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.1+(1-n.sub.2)c.sub.3.
[0174] In this configuration, as c.sub.2<0 and with
n.sub.1>n.sub.2, P.sub.2>P.sub.1>P.sub.3.
[0175] Alternatively, by having one of the shell surfaces be
toroidal rather than spherical, a cylindrical power such as
corresponding to a cylindrical prescription value can be
provided.
[0176] Considering the second optical lens configuration, and
further considering that the back lens shell has a toroidal shape
with a first curvature c.sub.3.sup.1 and a second curvature
c.sub.3.sup.2, the different power values are as following:
P.sub.1.sup.1=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3.sup.1
P.sub.2.sup.1=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.2)c.-
sub.3.sup.1
P.sub.3.sup.1=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.1+(1-n.sub.2)c.s-
ub.3.sup.1
P.sub.1.sup.2=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3.sup.2
P.sub.2.sup.2=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.2)c.-
sub.3.sup.2
P.sub.3.sup.2=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.1+(1-n.sub.2)c.s-
ub.3.sup.2
[0177] The superscript denotes the meridian in which the power is
calculated.
[0178] To obtain a specific prescription including a spherical
optical power P.sub.1.sup.1, a cylindrical optical power
P.sub.1.sup.1+Cyl and a cylindrical axis, the previous relations
become
P.sub.1.sup.1=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3.sup.1
P.sub.2.sup.1=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.2)c.-
sub.3.sup.1
P.sub.3.sup.1=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.1+(1-n.sub.2)c.s-
ub.3.sup.1
P.sub.1.sup.1+Cyl=(n.sub.1-1)c.sub.1+(1-n.sub.2)c.sub.3.sup.2
P.sub.2.sup.1+Cyl=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.22+(1-n.sub.-
2)c.sub.3.sup.2
P.sub.3.sup.1+Cyl=(n.sub.1-1)c.sub.1+(n.sub.2-n.sub.1)c.sub.1+(1-n.sub.2-
)c.sub.3.sup.2
[0179] The torus axis is simply set equal to the cylindrical
prescribed axis.
[0180] It shall be noted that in the previous examples, the
separator being planar, thus the interface between the two liquids
in the first state also being planar, may lead to large optical
aberrations if the front lens shell and the back lens shell are
purely spherical or toroidal.
[0181] FIG. 8 depicts a map of wearer power error and FIG. 9
depicts a map of unwanted astigmatism for an exemplary optical lens
according to the second optical lens configuration and a toroidal
back lens shell, with the following numerical values: n.sub.1=1.55,
n.sub.2=1.45, P.sub.1=-4 diopters, P2=-2 diopters, P.sub.3=-4.25
diopters and the cylinder is equal to 2 diopters.
[0182] It can be seen on FIG. 8 that a central area 500 (in light
grey) extending over about 30% of the surface of the exemplary
optical lens exhibits an optical power error which is under 0.25
diopters, however, top and bottom areas 510 (in dark grey) exhibit
an optical power error up to 1 diopter, which leads to an imperfect
correction when gazing up or down.
[0183] More importantly, it can be seen on FIG. 9 that a central
area 600 (in light grey) extending over about 20% of the surface of
the exemplary optical lens exhibits an unwanted astigmatism which
is under 0.25 diopters, while large values of unwanted astigmatism
over 1 diopter are reached in peripheral areas 610 (in dark grey),
which leads to a poor visual acuity in those regions.
[0184] This can be remedied by adding an appropriate freeform
surface to either the front surface of the front shell, or to the
back surface of the back shell.
[0185] To illustrate, an exemplary adapted optical lens is
considered, with the back surface of the back shell having a
freeform surface determined by using a non linear least squares
optimization of the power error and of the unwanted astigmatism
according to the following optimization problem:
min X .times. f .function. ( X ) = ( .alpha. , .beta. ) .di-elect
cons. K .times. [ PowerError .function. ( X , .alpha. , .beta. ) 2
+ UnwantedAstigmatism .function. ( X , .alpha. , .beta. ) 2 ]
##EQU00002##
[0186] K represents the set of all gaze directions of interest and
X are the parameters of the freeform surface. For solving this
optimization problem, many choices are acceptable.
[0187] FIG. 10 depicts a map of wearer power error and FIG. 11
depicts a map of unwanted astigmatism for an exemplary optical lens
according to the second optical lens configuration and a freeform
back lens shell obtained by solving the above optimization problem
using a Zernike layer of degree 7, with the following numerical
values: n.sub.1=1.55, n.sub.2=1.45, P.sub.1=-4 diopters, P.sub.2=-2
diopters, P.sub.3=-4.25 diopters and the cylinder is equal to 2
diopters.
[0188] It can be seen on FIG. 10 that the central area 500 of the
optical lens (in light grey) exhibiting an optical power error
below 0.25 diopters extends over 75% of the total surface of the
optical lens.
[0189] It can further be seen on FIG. 11 that the central area 600
(in light grey) of the optical lens exhibiting an unwanted
astigmatism below 0.25 diopters extends over 90% of the total
surface of the optical lens.
[0190] It shall be noted that all the equations above are designed
for configurations where the separator is planar. Of course the
separator can alternatively be for example spherical and the
membrane may be thermoformed to passively keep such spherical shape
in the first state. With a spherical separator, more flexibility is
allowable on the values of c.sub.1 and c.sub.3, also thinner lenses
can be allowed.
* * * * *